Nottingham Forest star Morgan Gibbs-White appeared to criticise the officiating in his side's defeat to Manchester United in a now-deleted social media post.
Forest came within minutes of forcing extra time at the City Ground, but for Casemiro to head in an 89th-minute winner to set up a quarter-final tie between Erik ten Hag's side and Liverpool.
The Brazilian midfielder headed in from Bruno Fernandes' low free kick, with the goal allowed to stand following a lengthy VAR check.
Raphael Varane was stood in an offside position when the cross came into the box, though didn't touch the ball. He was adjudged not to have interfered with play on the VAR check.
Gibbs-White, however, didn't take too kindly to the call, with the Forest midfielder likening the incident to one in the Carabao Cup final at the weekend.
Virgil van Dijk scored the winner for Liverpool in extra time, but thought he had netted in the second half of normal time but for his goal to be ruled out for offside in an off-the-ball incident.
VAR ruled that Wataru Endo had blocked Levi Colwill from an offside position, therefore interfering with play - a decision that received huge backlash during and after the game.
The same appeared to happen on Wednesday during the winning goal, but it was allowed to stand despite VAR being present in the ground.
With Casemiro's goal, Varane appeared to block the run of Felipe, who hit the ground, though he was adjudged not to have been involved in the play.
Gibbs-White shared his frustration on Instagram, sharing a picture of the two incidents side-by-side and looking similar.
United made hard work of the game on the night, with the likes of Sir Alex Ferguson and Sir David Brailsford in attendance following Sir Jim Ratcliffe's minority takeover last week.
They struggled again in attack in the absence of Rasmjus Hojlund, with Marcus Rashford finding it difficult to lead the line in a central role, but avoided extra time thanks to their defensive midfielder.
Alejandro Garnacho and Antony backed up Rashford, but also struggled to get into the game, with Antony taken off early for Amad Diallo.
United will take on rivals Manchester City next in the Premier League, with one eye on Liverpool and the FA Cup quarter-final at Old Trafford in just over two weeks' time.